1. Field of the Invention
The present invention relates to a method of manufacturing a mixed beverage, more specifically to a method of manufacturing a mixed beverage that offers an excellent flavor and superior preservation stability, and that contains vegetable juice and/or fruit juice and soybean protein, and to a mixed beverage that can be obtained by the manufacturing method.
2. Description of the Related Art
Soybean is an excellent food as a source of protein nutrition. Consumption of this protein as a drink is a preferable form. However, soy milk precipitates in the weak acidic region where preservation stability is high, and also it does not have a flavor favorable to many people in the neutral region and hence its application has been limited.
For applications of soybean protein in the weak acidic region, addition of a stabilizing agent such as pectin (Patent Document 1) and addition of an emulsifying agent such as saccharose fatty acid ester of HLB13 or greater (Patent Document 2) have been known. Moreover, a method of inhibiting agglutination of soybean protein by adjusting the condition of passing its isoelectric point (Patent Document 3, and Patent Document 4) has also been proposed.
Furthermore, there is also a method in which after polyanionic substances have been removed from or deactivated and/or polycationic substances have been added in the solution containing soybean protein, a heating process at a temperature greater than 100° C. is performed under acidic conditions (Patent Document 5).
Moreover, soybean contains approximately 2% phytic acid, and phosphate compounds such as this phytic acid cause an uncomfortable, heavy feeling in the stomach. Accordingly, low phytate soybean protein beverage that is obtained by applying a phytate degradative enzyme to the soybean protein is known (Patent Document 6).
Moreover, vegetable juice and fruit juice have conventionally been consumed as health drinks. However, when mixing this vegetable juice or fruit juice with soy milk, complexes are formed causing turbidity and precipitation, resulting in a decrease in their product value. A drink has been disclosed which, in order to prevent the occurrence of this turbidity and precipitation, uses vegetable juice and/or fruit juice that have been treated with carboxylic ester hydrolase, then subjected to pectinase treatment as necessary, to adjust the pH of the drink to not more than 4.0 (Patent Document 7).    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. Sho 54-52754    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. Sho 58-20180    Patent Document 3: Japanese Unexamined Patent Application, First Publication No. Hei 7-16084    Patent Document 4: Japanese Unexamined Patent Application, First Publication No. Hei 12-77    Patent Document 5: International Publication No. WO02/067690 Pamphlet    Patent Document 6: Japanese Unexamined Patent Application, First Publication No. 2002-262838    Patent Document 7: Japanese Unexamined Patent Application, First Publication No. 2001-340069
However, even soybean protein that has been designed for application in the acidic region is unable to sufficiently prevent precipitation when used as a mixed beverage with vegetable juice and/or fruit juice. Moreover, in the method of treating vegetable juice and/or fruit juice with carboxylic ester hydrolase, turbidity and precipitation cannot always be adequately prevented. Furthermore, in the method of treating with pectinase, the enzyme treatment needs to be performed twice, resulting in a problem in terms of economical efficiency and amount of work.
Accordingly, an object of the present invention is to provide a method of manufacturing a mixed beverage that offers an excellent flavor and superior preservation stability, and that contains vegetable juice and/or fruit juice and soybean protein, and to provide a mixed beverage that can be obtained by this manufacturing method.